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Date: Fri, 24 Sep 2010 09:37:49 +0100
From: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
Subject: Re: [Qemu-devel] [PATCH 1/7] qcow2: Make get_bits_from_size() common
Message-ID: <20100924083748.GA2218@stefan-thinkpad.transitives.com>
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To: malc <av1474@comtv.ru>
Cc: Kevin Wolf <kwolf@redhat.com>, Anthony Liguori <aliguori@us.ibm.com>, Avi Kivity <avi@redhat.com>, qemu-devel@nongnu.org, Christoph Hellwig <hch@lst.de>

On Fri, Sep 24, 2010 at 01:50:39AM +0400, malc wrote:
> On Thu, 23 Sep 2010, Stefan Hajnoczi wrote:
> 
> > The get_bits_from_size() calculates the log base-2 of a number.  This is
> > useful in bit manipulation code working with power-of-2s.
> > 
> > Currently used by qcow2 and needed by qed in a follow-on patch.
> 
> int ilog2 (size_t size)
> {
>     if (size & (size - 1))
>         return -1;
> 
>     return __builtin_ctzl (size);
> }
> 
> Ifdef WIN64 omitted for brevity.

What is the situation with WIN64?

Stefan